The present invention generally relates to medical devices and methods. More particularly, the present invention relates to apparatus and methods for the ultrasonically enhanced delivery of therapeutic or contrast agents within the vascular and lung areas or other corporeal lumens.
Despite the significant progress of medical technology, vascular and lung diseases, as well as arterial thrombosis (blood clots in arteries), remain frequent, costly and serious problems in health care. Current methods of treatment such as drugs, interventional devices, and/or bypass surgery are usually expensive and not always effective, even sometimes causing additional problems. For example, drugs can also dissolve beneficial clots or interventional devices can injure healthy tissue to cause potentially fatal bleeding complications or to form scarring or cellular growth which may itself eventually become a serious obstruction in, for example, a blood vessel (a process known as restenosis).
Ultrasonic energy has been used for enhancing the intravascular delivery of drug, to dissolve clot acoustically, disrupt mechanically and inhibit restenosis. Such energy can be delivered intravascularly using specialized catheters having ultrasonically vibrating surface at or near their distal ends. One type of ultrasonic catheter delivery system uses a wire or other axial transmission element to deliver energy from an ultrasonic energy source, located outside the patient to the internal organs, to desired corporeal lumens. (See, for example, U.S. Pat. Nos. 5,002,059, 5,324,255, 5,345,940, and 5,699,805, each of which is incorporated herein by reference.) Such catheters are rigid and cannot be easily inserted through narrow and tortuous vessels and may cause serious damage to vascular walls.
A second type of catheter has ultrasonic transducers mounted directly on their distal ends. See, for example; U.S. Pat. Nos. 5,362,309, 5,318,014, 5,315,998, 5,269,291, 5,197,946, 6,001,069, and 6,024,718, each of which is incorporated herein by reference. Despite enhanced safety and the fact that there is no need to employ a transmission element along the entire length, these catheters suffer from limited ultrasound energy, and the transducer-catheter design is still problematic.
Another type of catheter has an ultrasonic transducer or ultrasound transmission element with a central orifice in the distal end to impart ultrasonic energy into liquid and simultaneously deliver it to a corporeal lumen. See, for example, U.S. Pat. Nos. 5,735,811 and 5,197,946, each of which is incorporated herein by reference. Although these catheters are more effective and liquid delivery is more convenient, there are design difficulties and limitation of ultrasound energy from longitudinal waves.
It is an object of the invention to provide an improved method and device for catheter drug delivery.
It is also an object of this invention to provide a method and device for catheter drug delivery using ultrasound energy.
It is another object of the invention to mix different drugs ultrasonically and deliver them to a desired corporeal lumen ultrasonically.
It is a yet another object of the invention to mix drug-liquid solutions with a gas (for example, saline with oxygen) ultrasonically and deliver the mixture to a desired corporeal lumen ultrasonically.
It is a further object of the invention to provide a method and device for delivering drugs to an intravascular area or/and a corporeal lumen, to dissolve blood clots.
It is a yet further object of the invention to treat a blocked and narrowed blood vessel with ultrasound waves.
These and other objects of the invention will become more apparent from the discussion below.
The present invention relates to apparatus and method for the ultrasonically enhanced delivery of therapeutic or contrast agents within the vascular and lung area or other desired corporeal lumens. Ultrasonic waves are applied to a vascular area, lung or any corporeal lumen without requiring direct contact between ultrasound transducer tip and the patient""s body, particularly to dissolve blood clots.
According to the present invention, a catheter system comprises an ultrasound transducer having a distal tip with a radial surface and a distal end surface. The ultrasound transducer is disposed in a chamber at the proximal end of the catheter, and the transducer radiation surface or tip directs ultrasound waves or energy forward into the catheter coaxially via liquid. Longitudinal ultrasound waves induce wave motion in fluid adjacent to the transducer distal end. While particularly intended to enhance the absorption of therapeutic agents delivered to certain body lumens, the catheter system of the present invention is also useful for the delivery of ultrasonic energy to a desired location. The transducer radiation surface or transducer tip, may be cylindrical, flat, concave, convex, irregular or have a different shape-geometry to radiate ultrasound energy into catheter.
The catheter of the present invention may comprise a proximal tubing for delivering therapeutic agent from a reservoir by pump or syringe. The tubing may be located in front of or behind the radiation surface.
In a first embodiment of the invention, an ultrasound transducer and tip are mounted in a proximal portion of a catheter body, located outside of the body of a patient. The remainder of the catheter distal to the proximal portion may be inserted into a blood vessel or attached to a body lumen, to drive a therapeutic agent ultrasonically and/or deliver ultrasonic energy.
In a second embodiment, the distal tip of the transducer does not have an orifice, which is very important to create and deliver ultrasound energy fully to a vessel or body lumen.
In a third embodiment, the catheter system comprises a catheter body, mechanically coupled with an ultrasound transducer through a housing or tip node, which is where the transducer body is outside the catheter. In this way, the catheter body can be provided with two or more tubing inlets (sleeves) for different therapeutic agents, even one or more different gases such as oxygen, and agents to be mixed and delivered ultrasonically.
The catheter system of the invention is particularly advantageous on tissues for which local topical application of a therapeutic agent is desirable but contact with the tissue is to be avoided. Furthermore, ultrasound waves used in the method energize the drug, dissolve the clots and cause the penetration of the drug within the narrow and blocked vessels.